Humpback whale subspecies discovery

Populations of humpback whales in the North Pacific, North Atlantic and Southern Hemisphere oceans are much more distinct from each other than previously thought and should be recognised as separate subspecies, a new genetic study shows.

Known for their amazing acrobatics, humpback whales annually undertake the longest migration of any mammal between their winter breeding grounds and summer feeding grounds. Although they travel vast distances, it appears their populations do not cross paths. Understanding how connected these populations are has important implications for the recovery of these charismatic animals that were once devastated by hunting.

Lead author, Dr Jennifer Jackson of the British Antarctic Survey explains: “The colour of the bodies and undersides of the tail (the ‘flukes’) of humpback whales in the northern oceans tend to be much darker than those in the Southern Hemisphere. Until this study we didn’t realise that these kinds of subtle differences are actually a sign of long-term isolation between humpback populations in the three global ocean basins.

“We found that although female whales have crossed from one hemisphere to another at certain times in the last few thousand years, they generally stay in their ocean of birth. This isolation means they have been evolving semi-independently for a long time, so the humpbacks in the three global ocean basins should be classified as separate subspecies. This has implications for how we think about their conservation and recovery on a regional scale.”